CODEWITHSUNDEEP
c#gdi+gdi
user438959
user438959

Reputation: 141

Find the points on a bezier curve. (GDI+)

Can you please help me to accomplish this using c#.

I have a GDI+ call as below:

graphics.FillPie(Brushes.White, _
                 new Rectangle(0, 0, 400, 150), 0 - 90, 77.783651160272726f);

graphics.DrawArc(new System.Drawing.Pen(Brushes.Black, 2), _
                 new RectangleF(0, 0, 400, 150), 0 - 90, 77.783651160272726f);

My requirement is to find all the points along the bezier curve/shape(pie, arc).

i.e, I need to redraw the shape in my method, which accepts only a point array. I have only the rectangle co-ordinates, start angle and sweep angle with me. Can anyone let me know if there is any inbuild method in .net for calculating this or is there any easy method to find this one.

Please let me know if you need any other informations. Kindly help me as this is very critical for me as I am not a genious in Math.

Thanks in advance.

Regards, James

Upvotes: 0

Views: 3450

Answers (4)

Ran
Ran

Reputation: 6159

Do you really have to represent this as an array of points?

If you can be flexible on the signature of your method, and instead of Point[] accept a GraphicsPath, then you can represent this curve in C# by compining the two parts.

EDIT: Adding example

For example, you can create a GraphicsPath like this:

GraphicsPath path = new GraphicsPath();
path.AddPie(new Rectangle(0, 0, 400, 150), -90, 77.78f);
path.AddArc(new Rectangle(0, 0, 400, 150), -90, 77.78f);

You can later use it to draw graphics using the Graphics.DrawPath method, or access the graphics path data through the GraphicsPath.PathPoints, GraphicsPath.PathTypes and GraphicsPath.PointCount properties.

Upvotes: 1

Esme Povirk
Esme Povirk

Reputation: 3184

Add your arc/curve to a GraphicsPath object, use the Flatten method to approximate the Bezier curves in the path as line segments, and use the PathPoints property to get the array of points.

Upvotes: 1

John Joseph
John Joseph

Reputation: 61

I have done the math and created a function called BezierCoordinates in the below given article in code project.

BezierCurve

Its a solution done in C#, Displayed in Silverlight.

Upvotes: 3

C.Evenhuis
C.Evenhuis

Reputation: 26456

You'll need some math, but fortunately nothing crazy. This site explains how to draw a circle by calculating points on it:

http://www.nsbasic.com/palm/info/technotes/TN25a.htm

It's not in C# but should give you an idea of how it works. Math.Sin() and Math.Cos() are .NET's sin and cos methods.

Upvotes: 0

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